I recently purchased a YIHUA 995D SMD Rework Station and me being the geek that I am wanted to see if I could perhaps control it (via USB/ATMEGA) by using my PC and touch screen instead of physically doing so with my hands. Being able to control it via PC would allow me to mount the 995D under my desk and out of sight so that I have more room to work with on the top of my desk.

However, I have limited knowledge on "snooping" or "Reverse Engineering" and that is why I am posting my project ideas here in hopes that someone more knowledgeable will be able to let me know what all I need to do in order to accomplish my task.

I started out thinking I would just simply hook up the ATMEGA and just control the buttons/knobs and leave everything else as-is and just use a webcam focus only on the LCD to view what was on. Although that would work, its not ideal nor is it geeky enough ;D .

The LCD screen seems to be controlled by the chip Holtek ht1621b. The website for it defines it as a "RAM Mapping 32x4 LCD Controller for I/O MCU". Here is the datasheet for it.

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There also seems to be another chip which seems to be the main MCU? It's called the S3 Microcontrollers u820 s3f8s19xzz-qr89 and it's datasheet.

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I've noticed that the IC above has a TX/RX UART line(s) looking at the diagram on page 9 of the datasheet.

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9.7 Port 4

Port 4 is an 8-bit I/O port with individually configurable pins. Port 4 pins are accessed directly by writing or reading the port 4 data register, P4 at location F5H in set 1, bank 1. P4.0–P4.7 can serve as inputs (with or without pullups) and outputs (push pull or open-drain). P4.7–P4.0 can serve as segment pins for LCD or you can configure the alternative functions:

Low-byte pins (P4.0-P4.3): T0OUT, TBOUT, TACLK, TACAP, TAOUT

High-byte pins (P4.4-P4.7): TxD1, RxD1, TxD0, RxD0

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Would this be something I could use to read and write the needed info/data to/from the micro controller chip? Would simply getting a USB to UART cable and hooking it up to those 2 pins work like it would when reading RS232 data on an Arduino?

I have high resolution images of the 995D here so that you can see the main board and all it has to offer for this to potentially happen.

So I am looking forward in learning from others on here as to what I could do for this to happen - or laugh at me and tell me its not possible at which will only get me more interested in doing it :).

Disclaimer: Also posted on these sites: electronics.stackexchange.com Electronicspoint.com electro-tech-online.com electronics-lab.com EEVBlog.com forum.allaboutcircuits.com AVRFreaks.net

  • \$\begingroup\$ Personally, I'd say forget it. I'm sure it's possible, but the amount of effort you'd have to go to is far, far more than it's worth and the additional parts you'd have to add would probably cost more than the soldering station itself, especially given that it's a yihua. \$\endgroup\$ – Hearth Apr 12 at 4:25
  • \$\begingroup\$ If you’re serious, you would have sketched out the schematic and figured out how it worked. Posting some pics of the ics then asking how to go about it is lame. Be prepared to put in some work. If it were me, i’d have a esp32 hosting a webpage with the screen and controls. Replicating the temperature control whilst easy has no real gain unless i was to spin a new pcb. \$\endgroup\$ – Kartman Apr 12 at 4:52
  • \$\begingroup\$ @Kartman I've added more information and my thoughts on them, \$\endgroup\$ – StealthRT Apr 12 at 18:45
  • \$\begingroup\$ It is unlikely you’ll get the code out of the micro, so you’re wasting effort and bits posting data on the micro. Start with the schematic. If you can’t draw the schematic, choose another project. \$\endgroup\$ – Kartman Apr 12 at 21:52

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